CVE-2021-47631

In the Linux kernel, the following vulnerability has been resolved:

ARM: davinci: da850-evm: Avoid NULL pointer dereference

With newer versions of GCC, there is a panic in da850_evm_config_emac() when booting multi_v5_defconfig in QEMU under the palmetto-bmc machine:

Unable to handle kernel NULL pointer dereference at virtual address 00000020 pgd = (ptrval) [00000020] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT ARM Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 5.15.0 #1 Hardware name: Generic DT based system PC is at da850_evm_config_emac+0x1c/0x120 LR is at do_one_initcall+0x50/0x1e0

The emac_pdata pointer in soc_info is NULL because davinci_soc_info only gets populated on davinci machines but da850_evm_config_emac() is called on all machines via device_initcall().

Move the rmii_en assignment below the machine check so that it is only dereferenced when running on a supported SoC.

Weakness

The product dereferences a pointer that it expects to be valid but is NULL.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/0940795c6834fbe7705acc5c3d4b2f7a5f67527a
• https://git.kernel.org/stable/c/0a312ec66a03133d28570f07bc52749ccfef54da
• https://git.kernel.org/stable/c/83a1cde5c74bfb44b49cb2a940d044bb2380f4ea
• https://git.kernel.org/stable/c/89931d4762572aaee6edbe5673d41f8082de110f
• https://git.kernel.org/stable/c/a12b356d45cbb6e8a1b718d1436b3d6239a862f3
• https://git.kernel.org/stable/c/c06f476e5b74bcabb8c4a2fba55864a37e62843b
• https://git.kernel.org/stable/c/c5628533a3ece64235d04fe11ec44d2be99e423d
• https://git.kernel.org/stable/c/c64e2ed5cc376e137e572babfd2edc38b2cfb61b